It has long been known that ventilating the attic space below a roof is highly desirable for a variety of reasons. These reasons include, for instance, lowering the temperature in the attic during summer months, lowering humidity levels in the attic during winter months, reducing heating and cooling costs in the living space below the attic, and reducing instances of mold and mildew growth within the attic. Accordingly, a wide variety of attic ventilators or vents have been developed over the years. These include passive attic vents through which hot air is exhausted by convection and active attic vents that forcefully draw air out of an attic space. Passive vents may include, for instance, dome vents and louver vents that are installed within a hole cut in the attic deck, or ridge vents that are installed over a slot cut along the ridge of a gable roof. Active vents also come in various forms, such as powered gable vents, wind turbine roof deck vents, and powered roof deck vents. Regardless of the type of vent selected, a corresponding area of inlet vents must be provided to allow fresh air to flow into the attic to replace the air expelled through the attic vent. These generally take the form of soffit vents that are installed over openings formed along the soffits of the roof. For roofs without soffits, fascia vents have been developed for the same purpose. In either event, fresh air is drawn into the attic in the regions of the soffits as stale air is exhausted to the environment.
More recently, to preserve electricity and help the environment, solar powered attic vents have been developed. These vents generally are provided with direct current (DC) electric fans that are driven with electricity generated by a photovoltaic solar panel, which may be mounted on the vent or in a location spaced from the vent. The Master Flow™ brand solar powered roof vent marketed by GAF Materials Corporation is one example of a solar powered roof vent. Some solar powered roof vents include batteries that are charged by the solar panel during sunlight so that some operational capacity is preserved for periods when the sun is not shining.
Solar powered attic vents are environmentally friendly, but nevertheless have certain inherent shortcomings. For instance, while they operate in a satisfactory manner in full sun, their efficiency diminishes significantly in cloudy conditions and even more significantly in overcast and rainy conditions. Furthermore, solar powered attic vents do not operate for long periods at night, even with stored battery backup. Attic vents powered by a home's AC supply grid are reliable in that they can operate in all conditions, but consume significant electrical power and thus are not as environmentally friendly as desired.
A need thus exists for a powered attic vent that exhibits the environmental responsibility of a solar attic vent while also being able to perform with the reliability of an AC powered attic vent when needed.